Depends on the DnD world, in Eberron or any other setting with large urban centers and a realtively common level of magic and Artificer is great. Even in less magic rich enviroments, the clever blacksmith is appropriate and very useful. An Artificer could get a job anywhere doing anything they wanted. Although he might wind up enslaved by someone following the practice of hobbeling smiths as a matter of national security.
Cleric is the second choice, again for universal application and all those things people have already said. Plus, one could be a cleric of just about anything in a fantasy setting, so you could follow almost any path you wished (again given the opportunity). For example sckeener said: "To make money, I wouldn't be a cleric...I'm not that amoral."
What no gods of Coin, Wealth, Buisness, or Profit in your campaign? Such a cleric would practically be required to make money.